This invention relates to improved processes for the precision forgoing of titanium or titanium alloy parts, and to the products produced by such forging.
Conventional methods of forging parts formed of titanium and titanium alloys are extremely expensive and difficult to perform and control, and in most instances produce parts which are not shaped precisely and which require substantial machining to remove large amounts of extra material after the forging process. The most common titanium forging method as currently used in the manufacture of high performance aircraft parts, involves the use of several differently shaped successive dies for each part, with the die cavity in a first of the dies being disigned to deform the titanium forging stock to a first shape defined by the configuration of that particular die, and with the next die being shaped to perform a next successive step in the forging deformation of the stock, and so on, until the final die utlimately gives the forged part a fully deformed shape. The dies employed for this purpose have normally required the parts to be desinged to have substantial draft for enabling their removal from the dies, and as previously indicated, the final product has in most cases been only roughly and not precision formed, necessitating extensive maching and other treatment of the part to give its surfaces accurate shapes required for the intended end use of the part.
There has been disclosed in U.S. Pat. No. 3,635,068 an "iso-thermal" process for forging titanium and titanium alloys, in which process the forging stock and a die structure are heated separtately to a forging temperature, following which the stock is placed in the die, with contained heating if desired, and forging force is applied to the die to deform the stock to a predetermined shape. However, this porcess does not produce what is referred to as a "net" shape, i.e., a finished and usable product. The surfaces of the forged part are not smooth enough to be used "as is," primarily because of lubricant build-up. Also, part distortion is inherent, and therefore it is necessary to "thicken" the walls with additional material which must be removed after forging as by machining.